So I'm really confused by now. Does spring encode the right way and the output of his method should be considered as legal url ? If yes, then why browser fails to make a request ? If no, what utility should be used for this purposes ?

Just to be sure, are those two + at the end of the url correct. I'm assuming this is some sort of a test, but all the other characters are repeated exactly 3 times and this one just twice, so could that be the problem?
– Teemu IlmonenJun 16 '16 at 11:14